I've been going to a few and I even have one of my own that I run twice a month at a local co-working space.

I don't know why anyone comes to either my meetup or the ones I go to, but they are 100% not people I want to hang out and drink with. Mostly middle-aged Asian and Indian men who are polite, quiet, socially distant, usually with no particular enthusiasm for the topic of the meetup. I don't know why they're there or why they're so numerous, but they're definitely not there to socialize and have fun.